Apparatus for controlling a stepping switch by means of a balanced bridge technique



y 6, 1955 H. HOFFMANN, JR 3,193,761 APPARATUS FOR CONTROLLING A STEFPING SWITCH BY MEANS OF A BALANCED BRIDGE TECHNIQUE Filed April 25. 1961 0 BA/YK M24 0 m4 we 0 l F &

INVENTOR.

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United States Patent 3,193,761 APPARATUS FOR CONTROLLING A STEPPING SWiTCH BY MEANS OF A BALANCED BRIDGE TECHNIQUE Henry Hoifmann, Jr., Rome, N.Y., assignor to the United States of America as represented by the Secretary of the Air Force Filed Apr. 25,1961, Ser. No. 105,519 1 Claim. (Cl. 323-97) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to control apparatus in general, and more particularly to a method and apparatus for controlling stepping and rotary drum type switches.

The primary object of this invention is to provide a novel method of controlling a stepping switch by means of a balanced bridge technique.

A further object of this invention is to provide apparatus adapted to control a stepping switch with maximum efiiciency and precision.

A still further object of this invention is to provide simplified apparatus for controlling a stepping switch.

Other objects of my invention, in addition to those recited above, will be apparent as said invention becomes better understood from an examination of the specification and claims taken in conjunction with the accompanying drawing.

The aforementioned drawing illustrates schematically, one presently preferred embodiment of my invention.

Basically, my invention comprehends a novel technique and apparatus for controlling a stepping switch by means of a balanced bridge circuit which includes the stepping switch activating coil and the stepping switch contacts. The underlying principle of my invention is that of pro viding, by means of an unbalanced bridge condition associated with all but the selected position contact, an electrical current adapted to energize the stepping switch actuating coil. The balanced bridge condition prevailing through the selected position contacts therefore de-activates the stepping switch activating coil, causing the switch to stop in the selected position.

Referring now to the accompanying drawing, there is illustrated, schematically, stepping switch 5 together with the associated circuitry as comprehended by my invention. The bank of contacts on stepping switch 5 that is designated CONTROL BANK has shorting means 28 atfixed to each step thereof. Batteries 36 and 37 provide the potential sources required to energize actuating coil 17. A resistive bridge is provided by fifty ohm resistors 13 and 14, and one hundred and forty ohm resistors 15 and 16. Unidirectional devices 18, 19, 20, and 21 control current fiow and may be diodes of the INESS type. Energizing activating coil 17 causes wipers 23, 2d, 25, 26 and 27 to progress simultaneously through the several contacts of their respective banks and return to the z position. Probe 6 provides a means for selecting the desired stepping switch position. Spring 7 keeps switch 8 open until probe 6 is pressed onto the selected contact of stepping switch ICC 5. Insulating material 33 ensures electrical isolation of switch 8 from positive terminal 9 of battery 36.

In operation, probe 6 is pressed onto a contact that is connected tothe desired step; in the present case step 5 of bank No. 1. Switch 8 is then closed by the compression of spring 7, thereby closing a circuit adapted to energize actuating coil 17. This circuit is traceable through switch 8 by Way of resistor 16, coil 17, and resistor 13, all three of which units are serially connected to battery 37 by way of the positive terminal 12 of battery 37. Activating coil 17, thus energized, causes wipers 23, 24, 25, 26, 27 to advance off the z positions. The stepping switch can now advance continuously by activation through wiper 23 and the shorted contacts of the control bank. When the stepping switch has advanced to a position which allows the positive voltage on probe 6 (that is, the potential from positive terminal 9 of battery 36) to be applied to resistor 14 through the contacts of step No. 5 of bank No. 1 and diode 21, the resistive bridge circuit balances and de-activates actuating coil 17. The switch then ceases to advance until probe 6 is removed or placed on another step at which time the coil 17 is reenergized by way of battery 12, units 16 and 13, and switch 23. Removal of probe 6 allows the stepping switch to continue advancing through the entire circular sweep of 360 degrees, until it returns to the 2 position. It will be understood that coil 17, so-called, will have the capability of causing full rotation of all switch arms through a complete circular path, until it breaks its own circuit by returning to the dead post Z.

There has thus been described the novel techniques and apparatus whereby the several objects of my invention are accomplished. While a specific simplified embodiment has been described by Way of illustration, it is not intended'that my invention be limited thereto. Therefore, since it will be readily apparent to those skilled in the art that many changes may be made without departing from the spirit and scope of my invention, it should be understood that said invention includes all modifications and equivalents which fall within the scope of the appended claim.

What is claimed is:-

Means for controlling a stepping switch having a plurality of contact-sweeping arms and a single electrical actuating coil for all of said arms, said means comprising a plurality of step position contacts, means for putting said actuating coil in a resistive bridge circuit, means for initiating cyclic progression of said stepping switch by un balancing said bridge circuit, means for arresting said progression with a balancing potential applied to said bridge through the selected step position contact, and means for allowing said switch to return to its original position by removing said balancing potential.

References Cited by the Examiner UNITED STATES PATENTS 3,010,059 11/61 McLaughlin et a1 318-21 LLOYD MCCOLLUM, Primary Examiner.

MILTON 0. HIRSHFIELD, Examiner. 

